Automatic Signal Analysis with LabVIEW

[Mike415]

I have LabVIEW Basic right now, but my task is to pull data off of an impedance analyzer and analyze the data.  What it needs to get to in the end is to pull points off the graph (Impedance etc. per Frequency) and then find two humps in the data (Not the only two humps, but generally they are in about the same range ).  It will need to analyze this and determine if it fits a certain criteria (ie. the humps have no more then a 30ohm difference in their max values. They are in the correct locations. Etc.) From what I gather I will need LabVIEW FULL.  Will tone measurements/other analysis be used for this? Or maybe Matlab integration?  I'm trying to figure out some basics and if we need to buy the FULL version.  The attached picture is the humps Im trying to analyze.Thanks


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[MikeS81]

Hi Mike, now my question from yesterday is answered. :smileyhappy: The difference between the values is maximum 30 Ohm. :smileyhappy: You can use a function with search for a local maximum. You can use a for loop to go through all you values.Mike

[Mike415]

Hi I have tried using Tone Measurements to find the maximum amplitudes between certain frequencies, but it doesn't pick up the right data and I'm having a hard time connecting the data I want.  I attached an image of where I'm at with no success.  What do you mean a function with search for a local maximum?  I thought the tone measurement was meant for what I'm trying to do.  Also since Im using the Evaluation version.  To do what I want, will I need the basic or full version of LabVIEW? 


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[Mike415]

After a bit more research I see there is a peak detection.  Is this of any help to me?

[Pie56694]

Hi Mike415,Here's another <a href="http://forums.ni.com/ni/board/message?board.id=290&amp;message.id=922&amp;query.id=8953#M922" target="_blank">thread</a> that used the peak detector.&nbsp; Perhaps it helps.

[Mike415]

Thanks for the link and example, but my data is in the form of XY plots, is this an issue because I have been having trouble hooking it up?&nbsp; The circled area is the data I'm trying to analyze. Thanks


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[Pie56694]

Hi Mike415,It won't work as-is.&nbsp; The Peak Detector VI takes a 1D array (typically the Y values from waveform data).&nbsp; You could build an array from your Y values, then pass it to the Peak Detector VI.&nbsp; I hope this helps.

[Mike415]

Is there a way to use both the Y Values (Ohm Magnitude) and still retain the frequency that these values occur at? Thanks

[Pie56694]

Hi Mike415,This can be done, but it's not built-into the Peak Detector.&nbsp; For example, if you wanted to measure when the peak occurred, you must use the formula provided in the detailed help file for the Peak Detector VI.&nbsp; In your case, the Peak Detector return is an index into the Y array.&nbsp; The index identifies the peak.&nbsp; You could then use the index as an offset into the frequency array to establish what frequency corresponds to the peak.&nbsp; I hope this helps.